UK distributor and RC manufacturer RadioC has its newest Drone Lab lipo packs out on the market. The Drone Lab series is specifically designed for use in race quads. This review looks at the 1500 mAh version of the 4 cell pack.
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Some competitors almost started a contest on the „most beautiful“ lipo. Well RadioC is taking the other route, aware of the fact not to win any design prices. That said: The Drone Lab packs come in a simple black shrink wrap. A blue-ish sticker on the front – that’s it. As a purist I kind of like that approach.
The Drone Lab 50-100C pack is a standard 4S1P config flight pack for high power use. A foam layer on the front and back provides extra impact protection on the cell edges.
Build Quality: Very good. Pack feels very well made on the outside. Connection terminal looks solid.
Plugs: The Drone Lab pack comes with standard XT60 connectors* equipped.
Cables: RadioC uses 12 AWG wires on this packs. The high flexible silicon layer is rated up to 200°C. Cable length is about 9 centimeters.
Balacing plugs: Standard XT-system*. Balance wires are rather short (4,5 cm) which is a benefit in terms of getting them out of the prop-range on the aircraft. Main power line is coming out of the top, balancing wires are connected at the bottom.
The battery followed the standard break-in-process: The pack is charged at a rate of 1C until CV-phase ends with current of 1/10C. The break-in phase consists of four charging cycles at 1C and four corresponding discharges at 1 C / 4C / 10C and 20 C.
Anomalies: No anomalies during break-in.
Internal resistance measurements during break-in phase
|Cycle||Cell 1||Cell 2||Cell 3||Cell 4||Total|
|After first charge||2.3||2.7||2.9||2.7||10.0|
|After second charge||2.4||2.7||2.7||2.7||10.2|
|After third charge||2.4||2.5||3.6||2.7||11.2|
|After fourth charge||2.5||3.1||2.6||2.6||10.8|
CV-Phase is short on this cell type. Balacing in normal mode took 1:32 min. Cell drift during charge was unobtrusive. This is for 1C charge (1,5 A).
The main part of this battery test will consists of different load test settings showing the battery performance. Constant load testing is used to judge the advertised C-ratings as well as look at cell drift under high loads. We also check on internal resistance once more. Next up is the dynamic current test, which simulates a „real“ flight with changing (=dynamic) loads. For test methodology please check the dedicated methodology page!
Constant Load Testing
Constant load testing follows a certain load pattern of different constant currents. Base load is 10 C. Current pulses at 50 C, 35 C, 20 C and 30 C are maintained for time intervals between 10 and 20 seconds. For more details please refer to the test methodology page.
During this test the pack delivered 1023 mAh. This is 68,2 % of nominal capacity. A solid value.
Average cell voltages
The following table lists the average voltages per cell, of the total pack, as well as the averaged value per cell as fraction of total voltage during phase of active load.
|Cell 1||Cell 2||Cell 3||Cell 4||Total||Average per cell|
|Avg. Voltages||3,724 V||3,725 V||3,69 V||3,725 V||14,864 V||3,716 V|
Just looking at average values the DroneLab pack performs good. Three cells stayed well above 3,7 V on average. An average value above 3,74 V / cell can be considered very good. Cell #3 dropped below the benchmark of 3,7 V / cell, though.
Exceptionally interesting when testing a battery under a constant load for a longer period of time: the lowest voltage per cell just before load impulse is disabled. On top, you should have look at voltage recovery rate, that is: how fast do cell voltages rise again once load impulse is cut.
|Phase||Cell 1||Cell 2||Cell 3||Cell 4||Total|
|End of 50 C||3,399 V||3,406 V||3,348 V||3,459 V||13,612 V|
|End of 35 C||3,45 V||3,459 V||3,426 V||3,502 V||13,837 V|
|End of 20 C||3,414 V||3,439 V||3,289 V||3,480 V||13,623 V|
|End of 30 C||–||–||–||–|
Voltage sag is relatively high on the DroneLab 1500 mAh pack. Cell voltages went way below the 3,5 V/cell benchmark on all three load cycles. The pack seems a little overwhelmed by the demanded currents.
Average voltage recovery per second
Those values are specific to the test setting and not valid for the pack in general! Still they allow an estimated guess about how fast voltages rise again after current spikes.
|Cell 1||Cell 2||Cell 3||Cell 4||Total|
|Avg. Recovery||0,0542 V / s||0,053 V / s||0,0568 V / s||0,0431 V / s||0,2071 V /s|
Strong voltage drops correspond to high recovery rates within five seconds after the load impulse is cut-off. Recovery is made to a normale level rather quick.
IR measurement is conducted using the four current pulses. Resistance for each cell is calculated in all four discharge phases. Shown values are averaged to cancel out different temperature points due to different discharge states during measurements.
Interpretation: The internal resistance of 3.47 mΩ average per cell indicates a „true“ C-rating of around 34 C (50.9 A). This is on the conservative side and represents a current draw that will make the pack last for a long time. See load testing for further categorization. This categorization helps explaining the heavy voltage sags as the first load impulse (75 A) and the second cycle (52,5 A) go way beyond what should be demanded from this pack (even if both pulses a within the claimed specs).
Cell drift under load
|Discharge Phase||50 C||35 C||20 C||30 C|
|Max Cell drift (V)||0,126 V||0,076 V||0,061 V||–|
Cell drift is strong especially on first discharge pulse (50 C) as this simply goes beyond the packs real capabilities.
Key Temperature Facts
Max. temp during discharge was around 60,4 °C on side of pack. This would have resulted in a cut-off, but cell voltage rule has been applied just a little before that. Note that heating of stressed LiPo packs will continue for some more time even when load is cut. This pack has to be cooled down actively immediately as temperature was on its way to 70°C.
The following chart shows all reviewed LiPos in the same product segment for direct comparison of performance. Higher values under load are better.
Constant 25 C Discharge
Pretty much a standard benchmark in the LiPo industry.
Cut-Off /warning value for this battery should be chosen 3,5 V minimum. After this point voltage drops quick. The battery provided 995 mAh (66,3 %) during the 25 C discharge.
Comparison of different reviewed 1500 mAh batteries under 25 C load.
Dynamic Load Testing
The dynamic load testing setting consists of two separate discharge scenarios that have been developed of two different real-life FPV flights. Pattern one represents a high speed low proximity flight around the open field with some hovering to the end. Average load is around 22 A. Second pattern is a free-style flight around trees in the park with some current spikes near 70 A. Average load on this flight is around 13 A due to longer floating periods.
During the test of pattern 1 the pack delivered 1018 mAh. This is 67,8 % of nominal capacity. Still a good value. In patter 2 testing 1022 mAh (68,13 %) could be used until first cell reached cut-off voltage.
The following charts give an overview of all tested packs in the 1500 mAh class so far.
The last chart of this review sums up the usable capacity during all four load scenarios. Please note that this is only the capacity consumed by the electronic load! There are losses due to heating of the pack, which could be approximated (see testing methodology page). All four tests are cut when any cell goes below cut-off voltage of 3,3 V (or pack goes above 58 °C on any of the three probes). If you would push further and go down to 3,0 V/cell you will be able to squeeze out some mAh more, but at the cost of excessive heat generation and shortening of pack life-span. This value will most likely differ from what you get when flying on a quad as most people don’t monitor voltage on a per cell basis and therefore don’t even notice if voltage drops below 3,3 V/cell during punsh-outs (what’s not necessarily a good thing, though). For comparison, used capacity until 3,3 V/cell is reached is the base line in all battery reviews on Drone-Zone.de.
The DroneLab 4S 1500 mAh 50-100 C battery is a usual sized pack with a nice capacity to weight ratio of 9.4 mAh/g. The measurements are standard for the 1500 mAh class. Overall build quality is good. The design is best described as modest. Perfect for everybody looking to put a black pack on there full carbon style mini quad! Voltages drop quiet happy under bigger loads. As most of the packs in this performance class the C rating is a little over the top. If long term continuous currents are needed, make sure to stay within the real rating of around 34 C. Otherwise the pack will have trouble to keep up with demanded currents. You will see excessive heat development (over 60 °C if not cooled properly) and voltage sags a lot. Once cell voltage goes below 3,5 V its time to come in for landing quiet fast for sure. Pricing of the DroneLab 4S 1500 mAh 50-100 C battery is still interesting. For around 20 € this pack is highly competitively priced and costs almost the same than the 1300 mAh version of the DroneLab family. If you need the extra capacity and only handle medium currents (well within the 34 C maximum) go for this pack. Don’t expect it’s performance to scale linearly compared to the 1300 mAh version, though. For the price tag this pack is still worth it!
Other packs of this line up tested: